chore: Move FetchUtil to util folder.

src/util/FetchUtil.ts

@@ -0,0 +1,29 @@
+import fetch from '@rdfjs/fetch';
+import type { DatasetResponse } from '@rdfjs/fetch-lite';
+import type { Dataset } from 'rdf-js';
+import { getLoggerFor } from '../logging/LogUtil';
+import { createErrorMessage } from './errors/ErrorUtil';
+
+const logger = getLoggerFor('FetchUtil');
+
+/**
+ * Fetches an RDF dataset from the given URL.
+ */
+export async function fetchDataset(url: string): Promise<Dataset> {
+  let rawResponse: DatasetResponse<Dataset>;
+  try {
+    rawResponse = (await fetch(url)) as DatasetResponse<Dataset>;
+  } catch (err: unknown) {
+    logger.error(`Cannot fetch ${url}: ${createErrorMessage(err)}`);
+    throw new Error(`Cannot fetch ${url}`);
+  }
+  let dataset: Dataset;
+  try {
+    dataset = await rawResponse.dataset();
+  } catch (err: unknown) {
+    logger.error(`Could not parse RDF in ${url}: ${createErrorMessage(err)}`);
+    // Keeping the error message the same to prevent leaking possible information about intranet
+    throw new Error(`Cannot fetch ${url}`);
+  }
+  return dataset;
+}